Bullet traps per se are well known devices which have been used for many years by firearm manufacturers and users (the latter including firing ranges operated by military installations, police departments, rifle and pistol clubs, and the like) who are faced either with the need to proof, function fire and target firearms such as handguns, rifles and shotguns or with the task of simply collecting spent bullets fired on the range. In this context, "proof" means test firing a firearm at a higher load of ammunition, usually 40% greater, than the regular load specified for the barrel of that firearm; "function fire" means test firing the firearm through its full cycle of functions; and "target" means test firing the firearm for accuracy. The objectives of such devices have been to provide means located at a relatively short distance from the shooter to catch the lead or other types of bullets (jacketed or unjacketed) and prevent either the ricochet of a whole bullet or a large fragment thereof or the backsplattering of numerous small metal particles, which could return with enough energy to cause injury to the shooter or innocent bystanders, and to collect the waste lead, brass and jacket material. The known types of bullets traps have run the gamut from wood boards to sand-filled boxes to metallic funnel and deceleration chamber combinations, and their structural and functional characteristics as well as their drawbacks and disadvantages are set forth in U.S. Pat. Nos. 5,070,763, 5,113,700 and 5,121,671, to which reference may be had for the relevant details.
The type of bullet trap according to the invention disclosed in U.S. Pat. Nos. 5,070,763, 5,113,700 and 5,121,671 is designed to overcome those drawbacks and disadvantages and to be used with all types of manual firearms (including handguns, rifles, shotguns, elephant guns, and the like) and with all types of ammunition (ranging from airgun pellets up to and including armor-piercing bullets). To this end, the trap (like many of the known "funnel and chamber" types of traps) has a first pair of spaced, flat, preferably metal plates located, respectively, above and below the path of flight of a bullet being fired into the trap and a second pair of spaced, flat, preferably metal plates arranged transverse (usually vertically) to the first plates on opposite sides of the bullet flight path, with the two pairs of plates defining, respectively, the upper and lower walls and the right and left side walls of a passageway having at its front end an entrance opening (where a target may be located) and at its rear end an exit opening or throat, through both of which openings the bullet can pass. The trap also includes a spent bullet deceleration and energy-dissipating chamber the circumferential, likewise preferably metal boundary wall of which is of generally spiral configuration having a horizontal axis and the opposite end walls of which are constituted by portions adjuncts of the respective second plates, with the passageway communicating with the chamber through the throat substantially tangentially of the chamber at the bottom region thereof.
In that trap, the plates defining the upper and lower walls of the passageway, in order to minimize bouncing of the bullet back and forth during its travel through the passageway, are oriented at respective relatively low angles of inclination to the horizontal ranging up to about 15.degree. (as explained in those patents, the angle of inclination may actually be as low as 0.degree., although that is not preferred) and the radius of curvature of the chamber wall at the initial as well as at all subsequent parts thereof is such as to keep the maximum amount of the side of the bullet presented to the chamber wall during its travel along those parts of the latter. The significance of this arrangement is that the shock of the bullet is distributed more evenly along the chamber wall and over a larger surface area thereof, and especially so in the initial part of the chamber wall, by virtue of which any potentially destructive tumbling of the bullet because of its nose digging into the chamber wall is prevented.
Moreover, in almost all forms of the trap (except when it is designed solely for use in catching airgun-fired projectiles such as pellets or BB's and may be made of a self-lubricating plastic material), a spray nozzle arrangement is provided within the deceleration chamber substantially axially thereof for directing a liquid lubricating fluid, preferably a white water lubricant (consisting of, for example, 4 parts water and 1 part mineral oil), against the initial part of the interior surface of the circumferential boundary wall of the deceleration chamber. The liquid, after having lubricated the initial part of the said boundary wall surface of the chamber and any bullets circumnavigating the chamber (it will be understood, in this regard, that the rapidly moving bullets pick up and carry along some of the liquid lubricant when passing through it, which ensures that the lubricant will be effective to reduce friction between the bullets and even those regions of the surface of the circumferential boundary wall of the chamber which the spray may not have contacted directly), flows downwardly in the chamber toward the bottom thereof, ultimately flowing out of the chamber and into the passageway through the throat thereof and then along the lower first plate to a collecting vessel. The "wet" trap thus is designed not only to minimize the metal to metal contact between the bullets and the metal surfaces along which they move, with the result that scoring and erosion of those surfaces as well as the generation of lead dust, if the bullets are made of lead, are reduced as far as possible, but also to ensure that shells, casings, spent bullets, any lead dust that is generated, and even any fragments of a larger size that might split off from the bullets, are engulfed in the liquid and are flushed thereby along the lower first plate of the passageway and into the collecting vessel. Preferably, the spray nozzle system is interconnected with the collecting vessel by suitable piping and a pump so that the liquid lubricating fluid, after separation of solids therefrom in the collecting vessel, can be recirculated from the latter to the spray nozzle conduit.
The advantages of the bullet traps disclosed and claimed in the said in U.S. Pat. Nos. 5,070,763, 5,113,700 and 5,121,671 are manifold. Very significantly, the traps are relatively inexpensive to manufacture, can be constructed for transportability and ease of installation, and do not require the provision of thick walls, sand mounds or like back-up structures. Also, the traps are multi-functional and permit proofing, function firing and targeting of handguns, shotgun and rifles (including high powered rifles) in one system, so that expenses that might have to be incurred in connection with the known types of bullet traps for providing duplicate separate systems for function firing, targeting and proof testing can be avoided. Moreover, whereas for safety reasons high powered rifles conventionally are test-fired only at outdoor long-distance firing ranges, the use of an appropriate version of these traps permits test-firing of such rifles to be safely performed even in a relatively small room with a distance of only 75 feet (22.86 m) or less between the muzzle of the gun and the trap.
Thus, since the traps can withstand even such high energy ammunition as 30.06 NATO armor-piercing bullets, 600-grain elephant gun bullets, and the like, wear and tear on the traps, maintenance requirements therefor, and the need for periodic replacement of parts of the traps (in particular the plates defining the upper and lower walls of the passageway and the circumferential boundary wall of the deceleration chamber) and the attendant costs thereof are all greatly reduced if not eliminated altogether. Still further, when a bullet is fired into such a "wet" trap, any lead dust generated in the course of the movement of the bullet along the metal surfaces of the trap is inevitably, and without any possibility of escape from the system, engulfed by and entrapped in the liquid lubricant sprayed out of the spray nozzles and continuously flowing downwardly over the chamber wall and from there on over the lower wall of the passageway. As a consequence, the lead dust is flushed by the liquid into the collecting vessel, where it settles out of the liquid and accumulates on the bottom of the vessel and hence cannot be dispersed from the vessel into the surrounding atmosphere. The so-achieved salvaging of the otherwise normally wasted lead dust for reuse in making bullets provides (apart from the environmental and safety benefits) an economic benefit as well, which has not been achievable with any of the previously known bullet traps.
Occasionally, however, some users of the bullet traps of the mentioned three patents have encountered a problem under certain conditions. The problem resulted from the fact that larger bullets fired from center fire handguns tend to flatten out somewhat when hitting up against one or the other of the passageway ramps of the trap, and, because of their lower speed and energy, they do not break up when running around the interior of the deceleration chamber but rather stay intact. Thus, when such bullets come out of the chamber and onto the lower passageway ramp for their intended movement along the latter down to the collecting vessel, they tend actually to remain in place on the ramp despite the flow of the liquid lubricant down the ramp, in effect adhering or binding to the ramp at their flat surface portions. While this is of no real consequence in single shot firings, in cases of automatic or continuous firing, i.e., when many rounds are fired in a substantially continuous burst or sequence from an automatic or semiautomatic pistol, the earlier fired bullets which have come out of the chamber and to a stop on the ramp will form a dam on the ramp. Any later incoming bullets hitting the dam will then be blocked from entering the deceleration chamber and may have their desired slightly deflected flight paths undersirably and unpredictably altered. As a result, the trap fails to function properly, which may lead to the trap being damaged and/or destroyed and could possibly also result in injury and/or death of the shooter or innocent bystanders. (It should be noted, merely in passing, that the rapid firing of center fire rifles is not beset by this problem because their bullets, having greater speed and energy, tend to disintegrate in the chamber into much smaller pieces or fragments which will not stick to the ramp but will be flushed along and off the same by the liquid lubricant flowing from the chamber and down the ramp to the collecting vessel.)
The sticking problem could, of course, have been solved by a suitably large increase of the liquid pressure and the liquid flow velocity in the circulating and flushing system. That, however, would have created additional energy requirements for the system, namely, larger pumps, larger pipes and valves, greater electric power sources, etc., and would also have led to increased size, weight and cost of the traps.